1. Field of the Invention
The present invention relates to a crossfeeder for accumulating and conveying items to a variable demand unit. More particularly, the present invention relates to an apparatus for supplying shells to a gun firing in an intermittent rapid fire mode by accumulating shells in a crossfeeding apparatus in order to accommodate variations in the gun's firing rate, and start-up and shut-down conditions.
2. Background of the Prior Art
Many different systems and equipment designs have been employed in the prior art for providing articles to a particular utilization point in a sequential manner. For example, cigarettes are manufactured by processes involving movement of individual cigarettes, or of an article that is to be eventually cut in half to form two cigarettes. The canning and bottling industries also move cans and bottles along some form of assembly line and, for instance, fill and seal a container at separate stations. In the military, armament has developed to the stage where rapid fire guns are in common use, and thus numerous designs have been proposed for the storage and transportation of shells to the gun.
All of these feed systems have a relatively common problem; namely, supplying shells to the guns in precise synchronization with gun demand. This problem is relatively easy when dealing with externally powered guns. In this type of gun, the feed system and gun are usually geared directly together and any convenient external power source may be used. Furthermore, these guns usually accelerate smoothly to full firing rate over a period of about 0.05 seconds, and the rate usually does not vary except during this start-up period.
Self powered guns present more difficult problems, as they actually start and stop once for every shell fired, regardless of the rate of fire. They start up and shut down almost instantly and are generally not capable of supplying enough excess power to drive a feed system. Thus, an auxiliary power source must be employed to drive the feed system, and it must be synchronized with the gun demand. It is also necessary to provide shell accumulation capacity between the gun and the majority of the shells stored by the feed system, as it is not practical to keep the entire complement of shells moving in synchronization with the gun.
In the cigarette industry, Stelzer in U.S. Pat. No. 2,874,701 proposes a double feeding system utilizing a first wheel to position cigarette filters and to feed a second wheel, and a feed on the second wheel to provide rolled tobacco at either end of the filter. The filter and cigarette units are combined, and then passed to a third wheel, wrapped, and eventually severed into individual cigarettes and packaged. This type of unit, however, utilizes nothing more than a gravity flow funnel type of feed system in order to supply the tobacco and the filter to the appropriate wheel. Thus it is inherently limited in speed, as the feeding can only be effected at the speed at which the slower of the two units falls into place. Additionally, there is no positive feed of either component, and a gravity feed system inherently has problems with jamming.
In the bottling and can filling industry, J. Kantor in U.S. Pat. No. 1,893,746 discloses a system that utilizes a star wheel to rotate bottles through the steps necessary to process them. An indexing system is provided in order to prevent damage to the system due to variations in bottle sizes and inaccuracies in indexing. However, like the prior disclosure, Kantor does not overcome supply and operation speed variation problems. In another system, P. W. Fleischer in U.S. Pat. No. 1,212,754 utilizes two separate gears in order to space cans apart even further and to speed them up. Again, however, the possibilities of accumulating cans to respond to variations in need is not addressed.
Meier et al. in U.S. Pat. No. 3,670,863 discloses a cartridge delivery system formed of an endless conveyor with individual "clam shell" cartridge holders that are maintained in a closed position during cartridge conveyance and open for cartridge release during rotation around an independent guide. The system, however, does not allow for accumulation of extra cartridges except in the flexibility of the conveyor, which is limited by the structure necessary to hold the clam shells closed.
Another system, described by Buschers et al. in U.S. Pat. No. 2,979,991, fires projectiles laterally to the direction of travel of an airplane using a Gatling gun type of system, and provides the projectiles to the system in pairs, one for firing in each direction, through the use of a chain ladder. The projectiles are guided into position by using pivoted shoes. The rate of firing of the gun, like the other known systems, is controlled by the shell delivery rate from the magazine, as no independent means are provided for accumulation between the magazine and the gun itself.
U.S. Pat. No. 3,800,658 of Hougland et al. takes a different approach and provides a drum type of ammunition storage system, eliminating the need for sprockets and scoop disc assemblies. This system serves to accelerate the speed of only the last few shells before firing, and to produce part of the acceleration by combining two different trains of shells. This type of system would overcome some of the surge problems noted above but, again, would not allow for automatic variable accumulation and storage which can provide greater flexibility in firing rates.